1. Field of the Invention
The present invention relates generally to a roofing fastener having a disk that distributes pressure over greater areas than do heads of nails alone when used to secure sheets of water-resistant materials to substrates such as wood and more specifically to roofing fasteners having resilient disks configured to moderate pressures along their peripheral edges to prevent damage to the material being supported by the roofing fasteners while preventing leaks through holes created in the material by the roofing fasteners.
2. Background Art
Roofing components are applied to the top of roofs for several reasons. First, the roofing materials prevent moisture from reaching an underlying support member such as concrete or plywood. Also, roofing materials serve to insulate a building from the outdoors.
With respect to underlying support members which are made of plywood or OSB, plywood, and about ½″ to ¾″ inches thick, a base ply sheet of felt-like material of fiberglass or organic material is commonly placed over the plywood. Roof fasteners are then installed through the base ply and into the plywood to hold the base ply to the support member. A layer of molten asphalt is then poured or brushed over the base ply and roofing fasteners. In some instances, a second layer of base ply sheets are placed over the first layer of asphalt while the asphalt it still hot. The asphalt thus holds the first and second layers of base ply sheet together.
In the event of high winds, it is important that the combination of the base ply sheet and asphalt be strongly anchored to the underlying roof substrate. With high winds, such as might accompany hurricanes, large relatively low-pressure conditions can be created above the asphalt/base ply roofing materials. This wind or low pressure can rip the asphalt/base ply sheet roofing materials off the underlying roofing substrate if not sufficiently anchored.
A common type of roofing fastener used today to hold plywood and asphalt roof materials to a roofing substrate is a nail with a disc 1″ to 1⅝ inches in diameter having a generally flat head. The fastener is pounded into the base ply and plywood. The nail penetrates the plywood and secures the disk, therefore securing the base-sheet to the plywood.
These cap nails have drawbacks. Often, they have limited capacity to secure the base sheet, because they will only provide 50-100 pounds of resistance. Tear out strength test results conducted on these roofing fasteners installed in plywood vary greatly from fastener to fastener due to inconsistency of plywood. Moreover, due to increasing losses in the insurance industry, pull out requirements for fasteners have been revised upward. Often these cap nails fail to meet the new and higher industry standards. Typically, these cap nails have pullout strength of about 50-100 pounds.
Problems exist with other fasteners as well. A roofing nail with a 1⅝″ metal disk adjacent to its head, have limited pull out rupture strength typically in the range of 70 to 100 pounds. Multiple component fasteners are also used which include a retaining disk with a central aperture, which receives a threaded fastener. This multiple piece construction increases the cost of making the fastener and complexity of installation. Further, even these multiple component fasteners also have difficulty in meeting today's desire for providing higher load values without pulling out or tearing the roofing material.
The present invention is intended to address deficiencies found in these above-described conventional fasteners.